Formulating a semi-empirical equation for the shearing modulus of rigid pavement slabs

Abstract

A rigid pavement consists of a subbase, base, and a surface in the form of concrete slabs with varying thicknesses and strengths. The design methods currently known are the AAHSTO, PCI, ACI, and others, which are traditionally based on analytical solutions of beams or long plates supported by an elastic foundation under static loads. Recently, research has emphasized dynamic modeling and analysis of loads. Other research focused on a parametric study to identify key aspects of the dynamic behavior of rigid pavement slabs on an elastic layer. The Pasternak model presented a spring layer and a shearing layer to simulate the dynamic behavior of the slab. A shearing layer contributes to dynamic behavior through the shearing modulus (G_max), where it plays a role in dynamic analysis. This research is purposed at formulating the empirical equation for the shear modulus of the subbase layer of toll road rigid pavement in Indonesia based on soil samples taken from beneath the rigid pavement. The result of this research shows that G_max values (unit MPa) based on Kakusho equations are 24.294 (max) and 16.325 (min), Marcuson’s are 32.015 (max) and 22.306 (min), Menard’s are 34.527 (max) and 10.634 (min). All G_max tend to be within similar corridors. While Hardin’s are 67.112 (max) and 31.982 (min), it tends to be higher than other G_max values above. Other result was a semi-empirical equation successfully developed to calculate G_max from plasticity index (Ip) : G_max = 0.0313(Ip)² - 3.1147Ip + 88.798. By having those results, designing a rigid pavement slab may be used above G_max values and equations to carry a dynamic analysis design.